This article presents how Paul, in 1 Thessalonians, executes the process of the formation of the Thessalonian community. Using the sociological concept of symbolic boundaries, it is argued that the resources - (1) the kerygmatic narrative, (2) the local narratives, and (3) the ethical norms - that Paul incorporates into the letter take an essential role to promote the converts to derive a cooperative identity from the community to which they belong and to strengthen the distinction between them and the larger society. By providing internal consensus and external separation, the resources serve to construct and maintain the Thessalonian community that is internally united and externally distinct.